The Central African Republic (CAR) has a serious onchocerciasis problem. The disease is endemic in three quarters of the country and there is considerable onchocercal blindness in the north-west. The low population density and extreme poverty (the CAR being one of the 20 poorest countries in the world) combine to make mass treatment with Mectizan (ivermectin, MSD) a challenge. Although planned, primary health care (PHC) is not widely developed in the country. Mectizan distribution was carried out in 1993-1994 by mobile teams in order to address the most urgent need, particularly in the north-west. Since then, the strategy has been one of community involvement, using village health workers, chosen by their own communities, to do the treatment. The system has been a stimulus to the development of PHC in some areas, as the co-ordinators of the Mectizan programme are often the only health personnel to visit every village. The long distances between health centres, with a mean of 45 km, are likely to be an obstacle to the population collecting their own Mectizan, within the self-treatment system otherwise in place. Operational research is planned to examine ways in which the population can contribute to cost recovery without there being a reduction in treatment coverage.